https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79815
Bug ID: 79815 Summary: gcc does not implement C++ standard 7.1.7.4.1 p5 correctly. Product: gcc Version: 7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: boostcpp at gmail dot com Target Milestone: --- ยง7.1.7.4.1 paragraph 5 said. >If the placeholder is the decltype(auto) type-specifier, T shall be the >placeholder alone. Following code shall be ill-formed if compiled with -std=c++14. Because it is not placeholder alone. int const i{} ; // ill-formed, But GCC accept this code. decltype(auto) const x = i ; Affect all version of GCC.